Automatic motor synchronization control



y 1946. w. P. LEAR- I AUTOMATIC MOTOR SYNCHRONIZATION CONTROL Filed Feb.3, 1944' INVENTOR. W/[l/ll/ f 154/? BY AITOLRNL'Y SEPWLIW Al JOKPZOUmob-OS All Patented July 2, 1946 AUTOMATIC MOTOR SYNCHRONIZATION c NTRoLWilliam P. Lear, North Hollywood, Calif; assignor, by mesne assignments,to Lear, Incorporated, Grand Rapids, Mich., a corporation of IllinoisApplication February 3, 1944, Serial No. 520,895

This invention relates to a reset synchronizins system, and moreparticularly to such a sys-.

tem wherein movable members may be manually or automatically aligned ata predetermined point in their path of travel.

The present invention is particularly useful i or controlling theposition of accessories aboard an aircraft. Aboard the larger airplanes,indicatlons of the reading of a master instrument are" usually repeatedat various points throughout the aircraft. Generally, wherev the numberof repeating instruments is not large, a telemetering system has beenused. However, where a relatively large number of repeating instrumentsare to be synchronized with a master instru- Claims. (Cl. 172239) Fig. 2is a schematic representation of a portion of another embodiment of theinvention.

Referring to Fig. 1 the invention is illustrat ed as employed forrepeating the bearing indications of a rotatable loop antenna In whichmay form part of an automatic radio direction finding system such asillustrated in my Patent No. 2,308,521, issued January 19, 1943, for"Automatic radlo direction indicator" which i assigned to t e sameassignee as this application. Remote indicators l5 and 26 are providedfor repeating ment, the load imposed on the telemetering transmitter bythe repeating instruments mayadversely affect the accuracy of therepeated indications.

For this purpose, the present invention comprises a plurality of remoteindicating instruments each of which is separately driven by its ownpower means.v As the power supply aboard aircraft is generally furnishedby a 28 volt battery, direct current motor are used as the power means.Synchronizing connection are provided between the direct current motorsfor the various instruments, to effect synchronous operation of theinstruments. Additionally, the present invention contemplates means formanually or automatically checking and restoring align ment between theinstruments at predetermined points in the path of travel of theindicating elements.

It is among the objects of thi invention to provide a resetsynchronization system for maintaining alignment between a plurality ofmovable elements; to provide such a system including independentlydirect current motor driven movable elements including synchronizingconnectlons between the motors for ali the elements; to provide such asystem including selectively operable means for automatically checkingand restoring alignment between the movable elements at a given point intheir paths of travel; to provide such a system including meanautomatically responsive to misalignment between the movable elementsfor restorin alignment therebetween;

shaft 1:. I 28 allow a relatively high speed motor to be used th bearingindications of antenna ID at points remote with respect to the antennaThe antenna it is mounted on a shaft I l and has a closed loop or coilwinding connected to slip rings i2 and i3. Brushes l4 and i6 engage ringl2 and I3 andare connected to leads ii and it,

which conduct the signals received by antenna it to the input of asuitable directional receiving system, not shown. A quadrantal errorcompensator, diagrammatically illustrated at 2!, is provided forcorrecting for the quadrantal errors in the directional indications ofantenna iii, before such bearin indications are transmitted tofu!- therassociated apparatus. The quadrantal error compensator may be of thetype disclosed and claimed in my Patent NO. 2,336,361 issued Decemher 7,1943, for Quadrantal compensators.

A. reversible direct current shunt motor 22 having an armature 23 and ashunt field winding '24 is provided to rotate antenna l0. Armature 23 isconnected to a shaft 25 which drives a shaft 26 through reductiongearing 21. A worm 28 on shaft 26 engages a worm gear 30 on loop antennaReduction gearing 21 and worm drive fOr rotating antenna m at a moderaterate.

Each remote indicator l5 and 20 comprises a rotatable pointer 3| or 32,respectively, cooperating with a dial 33 or 34. Pointer 3l i mounted ona rotatable shaft 35. A reversible direct current shunt motor 36 havingan armature 31 and a shunt field winding 38 is provided to rotatepointer 3|. For this purpose, armature r shaft 40 drives a shaft 4|through reduction gearing 42. A worm 43'on shaft 4| engages a worm ear44 on indicator shaft 35. Similarly, a reversible direct current shuntmotor 45 is provided to operate indicato 20. Motor 45 includes a shuntfield 46 and an armature 41 having a shaft 48 driving a second shaft 50through reduction gearing 5|. A worm 52 on shaft 53 engages a worm gear53 on indicator shaft 54 connected to rotatable pointer 32.

Synchronizing circuit connections are provided between the severalmotors 22, 38 and 45 to maintain indicators l5 and 20 in synchronousrotation with antenna 10. The synchronizing connections in the presentinstance may comprise slip rings 55, 56 and 51, each connected tocorresponding points in the armature windings 23, 31 and 41. Brushesengage each of the slip rings and are interconnected through a conductor58. If desired, more than one slip ring may be provided for eacharmature winding. With the described arrangement, if there is adiscrepancy between relative positions of the motor, a circulatingcurrent is set up in conductor 58 which tends to slow down or speed upthe motors with respect to the discrepancy in the angular position ofthe larger motor.

Each of the motors 22, 3B and 45 is arranged to be energized throughmotor control system I50 which may be the same as the motor controlsystem shown in Fig. 4 of my above referred to Patent No. 2,308,521. Asthe circuit connections in the motor control system are fully d bed. ins: i patent, only a thematic rep tion thereof is here provided. Motorcontr -l system EU is arranged to energiae either of a pair of relays Sior 82, connected to system M by conductors G3 and 54, respectively. Theopposite terminals of the relays are connected to ground at 65. Relays6i. and 82 have armatures 6S and 61 which normally engage back contactsHi and II connected to the positive terminal of a suitable source ofdirect current diagrammatically illustrated as a battery 12, which maybe the 28 volt aircraft battery. Front contacts 13 and H of relays GIand 62, respectively, are connected to ground 65. Armatures 56 and B1are connected through conductors 15 to conductors 16. Motor armatures28, 31 and H are connected in parallel across conductors Hi.

Field windings 24, 38 and 46 are connected in parallel throughconductors ll. One of the conductors I1 is connected by conductor 18 tothe positive terminal of battery 12, and the other conductor isconnected to ground at 80. A suitable control switch may be provided inthe conductor 18 in a well known manner.

The several motors are reversible through reversal of the polarity ofthe motor armature terminals. The direction of rotation of the motors iscontrolled by the relays 6i and 52 connected to motor control system 60.As described in my Patent No. 2,308,521, displacement of antenna ID froma predetermined radio bearing position will cause energizationof itsassociated motor 22 in a direction to rotate the antenna to such bearingdirection. For instance, if the control signal is such as to energizerelay 5|, armature 56 will engage front contact 13, while armature 61will remain in engagement with back contact 1 I. This will connectconductors 16 respectively to the positive terminal of battery 12 and toground, thus energizing motors 22, 36 and 45. Upon deenergization ofrelay GI, armature 66 engages its back contact 10. A closed circuit isthus provided for the armature windings resulting in rapid dynamicbraking action causing substantially instantaneous stoppage of theelement driven by each motor, due to generator action of the motors asthe fields are still energized. Synchronizing connection 58 maintainssynchronous rotation of the motors.

The means for checking and resetting the alignment of antenna in andindicators i5 and at predetermined points will now be described. Thismeans comprises rotatable disks 8|, B2 and 83, operatively associatedwith antenna I0, indicator I5 and indicator 20, respectively. Each diskis provided with an abutment 84. Plungers 85, 86 and 81 in operativearrangement with each ab tment 84 and are normally in a position wherethey will'not engage the associated abutment. An energizing winding 90,BI and 82 is provided for each plunger 85, 8G and 81. One terminal ofeach energizing winding is connected to positive battery supply, asindicated. The other terminals of the windings are connected in parallelto a conductor 93 which is connected to a terminal 54 of a push button95. Push button 95 comprises a movable member 96 having spaced contacts91 and 98 connected respectively to the positive battery terminal and toground. Contact 88 is adapted to connect terminal 94 to ground, andcontact Si is adapted to connect one terminal of relay 62 to thepositive battery terminal through terminal iiiil and a conducto lill.

The described resettin" e folio turn motors iii. ii in a givendirection, such I. r. :ackwise. the same time, solenoid windings :"lli,iii and ill will be energised, their opposite terminals are connected toground through conductor 93 and contacts 94 and 98 of switch 95.Energization of the solenoids will move plungers 85, 3S and 81 into thepath of movement of abutments 8.

Assume that antenna Iil is out of alignment with indicators i5 and 20,as by being several degrees in advance thereof. Accordingly, abut ment84 on disk Bl will strike plunger and will arrest motion of antenna iiiuntil the abutments B4 on disks 82 and 83 likewise engage theirassoclated plungers 86 and ST. When all the abutments have engaged theirplungers, switch 55 may be opened and the system permitted to operate inthe normal manner. The abutments 84 on the several disks are sopositioned that when they engage their associated plungers, antenna iiiis aligned with indicators i5 and 20. Normally, such resetting operationneed take place only at infrequent intervals, due to the synchronizingcircuit connections, including the rings 55, 56. 51 and conductor 58.Such synchronizing circuit connections maintain the direct currentmotors 22, 36 and #5 in substantial synchronism at all times so thatindicators l5 and 20 faithfully rc- D at the varied indications ofantenna Ill.

The modified form of the invention illustrated in Fig. 2 operatesautomatically to cause necessary resetting of the alignment between theantenna and the indicators at least once during each revolution of suchelements. To simplify the drawing, the portion of Fig. 1 to the left ofthe broken vertical line has been omitted in Fig. 2, but it isunderstood to be the same as that shown in Fig. 1. Likewise,corresponding elements have been given the same reference characters inFig. 2. Antenna ill in Fig. 2 is provided with a disk I05, andindicators i5 and 28 are provided with disks I06 and I 01 respectively.These disks correspond to disks 8|. 82 and 81 of Fig. 1. Each of disksI05, I05 and H1! is electrically connected to ground as indicated atHi8, I09 and H0 respectively. Likewise. each disk is provided with acombined electrical contact and abutment member ill, H2 and H3respectively. These contact members are adapted to engage brushes ill, II5 and HE respectively fixed separately from contactslll, H2 and H3.

Plungers H1, H8 and ii! are provided for movement into abutting relationwith the several abutments. Each plunger i provided with an operatingwinding I20, [2! and I22. One terminal of each winding is connected toone of the brushes H4, H5 and H6. The other terminals of the windingsare individually connected to back contacts I23, I24 and I25 normallyengaged by an armature I26 associated with amarginal relay I21. A frontcontact I28 of relay I21 is connected to brush I I4 for a purpose to bedescribed hereinafter. Armature I28 is connected to one terminal ofrelay I21 and the opposite terminal of the relay is connected to asuitable source of current, such as a battery indicated at I36.

Operation of this embodiment of the invention is as follows. Marginalrelay I21 operates when the current flow through its.windings exceeds apredetermined value. Assume first that indicators I5 and are out ofalignment with each other and with antenna I0. and further, that antennaII'I leads indicator I5 which in turn leads indicator 20. If theelements are rotating in a clockwise direction, contact member III willengage member H4 and close a circuit through relay I21. However, thecurrent flow through the circuit will not be sufiicient to energizerelay I21, although solenoid I20 will be energized to move plunger II1into abutting relation with member II I and stop rotation of disk I05and antenna I0. Contact II2 next engages brush II5 energizing solenoidI2I and moving plunger IIB into abutment position with contact H2. Whenso connected, more current will flow through relay I21 through aparallel circuit, but still insufficient to cause operation of thisrelay. Finally, contact i Iii will engage brush. IIG energizing solenoidwinding I22 and movin plunger H9 into abutting relation with contact MS.This additional increment of current flow through relay I21 willincrease the total flow therethrough to a value sufficient to energizerelay I21. Armature I26 will thereupon be moved out of engagement withcontacts I23, I24 and I25, breaking the energizing circuits forsolenoids I20, Hi and i22. Movement' of antenna I0 and indicators i5 and29, which are now aligned, will be resumed. At the same time, armatureI25 engages front contact 628 to close a holding circuit for relay i21through contact I I I until this contacthas cleared plunger ii'i, atwhich time the holding circuit will be broken and armature I26 will moveinto engagement with its back contacts. The operation of relay i2! canbe controlled for any desired curr rent flow by provision of a suitableadjusting spring on the armature I26 as will be understood by thoseskilled in the art.

The described systems permit remote indications to be provided whereverdesired, without exerting a torque upon the master or controllingmember. This is true for the reason that each of the remote indicatorsis independently energized by its own motor, and the motorsare-maintained in substantial synchronism through the slip rings 55, 5Band 51. Additionally, in both embodiments of the invention, thealignment is either checked manually at desired intervals, orautomatically at least once during each revolution cycle of therotatable members.

While specific embodiments of the inevntion have been described toillustrate the application of the principles thereof, it will beunderstood by those skilled in the art that the invention may beotherwise embodied without departing from such principles. Y

What is claimed is:

1. A reset synchronizing system comprising, in combination a pluralityof movable elements; a plurality of direct current motors each operaasource of direct current; reset means connected, to such source; andmechanism operable by'said reset means for stopping motion of each ofsaid elements, during energization of said motors, at

a predetermined point in its travel, said predeten mined points being incoincidence.

3. A reset synchronizing system comprising, in combination a pluralityof rotatable elements; a plurality of direct current motors eachoperatively associated with one of said rotatable elements;synchronizing connections between said motors; means effective toconnect said motors to a source of direct current; an abutment memberrotatable with each of said rotatable elements; stop means operativelyassociated with each abutment member; and reset means operable toposition said stop means in the paths of said abutment members to arrestrotation of said elements, during energization of said motors, to alignthe same.

4. A reset synchronizing system comprising, in

combination a plurality of rotatable elements; a'

plurality of direct current motors each operatively associated with oneof said rotatable elements;

synchronizingconnections between said motors;

means effective to connect said motors to a source of direct current; anabutment member rotatable with each of said rotatable elements; stopmeans operatively associated with each abutment member; and electricallenergizable reset means connected to said source and operable, whenenergized, to position said stop means in the paths of said abutmentmembers to arrest rotation of said elements, during energization of saidmotors, to align the same.

5. A reset synchronizing system comprising, in combination a pluralityof rotatable elements; a plurality of direct current motors eachoperatively associatedwith one of said rotatable elements; synchronizingconnections between said motors; means effective to connect said motorsto a source of direct current; an abutment member rotatable with each ofsaid rotatable elements; plungers each operatively associatedwith anabutment member; solenoid means operable when energized to position saidplungers in the paths of said abutment members to arrest rotation ofsaid elements, during energization of said motors, to align the same;and reset means operable to energize said solenoids.

6. A reset synchronizing system comprising, in combination a pluralityof rotatable elements; a plurality of direct current motors eachoperatively associated with one of said rotatable elements;synchronizing connections between said motors; means effective toconnect said motors to a source of direct current; an abutment memberrotatable with each of said rotatable elements; plungers eachoperatively associated with an abutment member; solenoid means operablewhen energized to position said plunger; in the paths of said abutmentmembers to arrest rotation of said elements, during encrgizatlon of saidmotors, to align the same; and reset means operable to connect saidsolenoids to said source to energize said solenoids,

7. A reset synchronizing system comprising, in combination a pluralityof rotatable elements; a plurality of direct current motors eachoperatively associated with one of said rotatable elements;synchronizing connections between said motors; means eliective toconnect said motors to a source of direct current; a disk rotatable witheach of said rotatable elements; an abutment member on each disk, saidabutment members being aligned when said elements are aligned; stopmeans operatively associated with each abutment member; and reset meansoperable to position said stop means in the paths of said abutmentmembers to arrest rotation of said elements to align the same.

8. A reset synchronizing system comprising, in combination a pluralityof rotatable elements; a plurality of direct current motors eachopcratively associated with one of said rotatable ele ments;synchronizing connections between said said elements to align the same;and reset means operable to energize said solenoids.

9. A system for maintaining alignment between a plurality ofindependently movable elements comprising, in combination, a pluralityof revere" ible direct current motors each cperatively asso" ciated withone of such movable elements; selectively operable means effective toconnect said motors to a source of direct current for rotation in eitherdirection; reset means connected to such source and said selectivelyoperable means, said reset means being operative to energize saidinotors for rotation in one direction; and mechanism operable by saidreset means for stopping rotation of each of said elements at apredetermined point in its travel, said predetermined points being inalignment,

10. A reset synchronizing system comprising, in combination a pluralityof rotatable elements; a reversible direct current motor operativelyassociated with each of said rotatable elements; synchronizingconnections between the motors; selectively operable means effective toconnect said motors to such source for rotation in either direction; anabutment member rotatable with each of said rotatable elements; stopmeans operatively associated with each abutment member; and

manually operable means connected to such source and effective toenergize said motors for rotation in one direction and to position saidstop means in the paths of said abutment members to arrest rotation ofsaid elements to align the same.

ll; A reset synchronizing system comprising, in combination a pluralityof rotatable elements; a reversible direct current motor operativelyassociated with each of said rotatable elements; synchronizingconnections between the motors; selectively operable means efiective toconnect said motors to such source for rotation in either direction; adisk rotatable with each of said rotatable elements; an abutment memberon each disk, said iii) abutment members being aligned when saidelements are aligned; stop means operatively associated with eachabutment member; and manually operable means connected to such sourceand effective to energize said motors for rotation in one direction andto position said stop means in the paths of said abutment members toarrest rotation of said elements to align the same.

12. A reset synchronizing system comprising, in combination a pluralityof rotatable elements; a reversible direct current motor opera'tivelyassociated with each of said rotatable elements; synchronizingconnections between the motors; selectively operable means effective toconnect said motors to such source for rotation in either direction; anabutment member rotatable with each of said rotatable elements; plungerseach operatively associated with an abutment member; solenoid meansoperable when energized to position said plungers in the paths of saidabutment members to arrest rotation of said elements to align the same;and manually operable reset means for energizing said motors forrotation in one direction and to energize said solenoids,

13. A reset synchronizing system comprising, in combination a pluralityof rotatable elements; a plurality of motors each operatively associatedwith one of said rotatable elements; means effective to connect saidmotors to a source of current; an abutment member rotatable with each ofsaid rotatable elements; stop means operatively associated with eachabutment member; reset means automatically operable to position saidstop means in the paths oi said abutment members to arrest rotation ofsaid elements to align the same; said reset means being automaticalloperative in response to alignment of said elements to with draw saidstop means from the paths of said abutment members.

14. A reset synchronizing system comprising, in combination a pluralityof rotatable elements; a plurality of motors each operatively associatedwith one of said rotatable elements; means effective to connect saidmotors to a source of current; a disk rotatable with each of saidrotatable elements; an abutment member on each dish, said abutmentmembers being aligned when said elc ments are aligned; stop meansoperatively associated with each abutment member; reset meansautomatically operable to position said stop means in the paths of saidabutment members to arrest rotation of said elements to align the same;said reset means being automatically operative in response to alignmentof said elements to withdraw said stop means from the paths of saidabutment members.

15. A reset synchronizing system comprising, in combination a pluralityof rotatable elements; a plurality of motors each operatively associatedwith one of said rotatable elements; means effec tive to connect saidmotors to a source of current; a disk rotatable with each of saidrotatable ele' ments; an abutment member on each disk, said abutmentmembers being aligned when said elements are aligned; plungers eachoperatively associated with an abutment member; solenoid means operablewhen energized to position said plungers in the paths of said abutmentmembers to arrest rotation of said elements to align the same; and resetmeans automaticall operable to energize said solenoids; said reset meansbeing automatically operative in response to alignment of said elementsto deenergize said solenoids.

WIN AM P. LEAR.

